Most current cartridge type percussion and electrical primer ignited ammunition use lead (Pb) based primers that release toxic air-borne lead. The United States military services expend more than 20 million such rounds per year and each year non-military rounds expended are in the hundreds of millions. The conventional primer compositions for such ammunition are based on lead azide, lead styphnate, and barium nitrate [a) Olin MSDS No. 00061.001, http://www.winchester.com/pdf/MsdsPDF/msds_w61.pdf last accessed Jun. 15, 2007, b) “Combustion Products of Propellants and Ammunition”, D. B. Kirchner, J. C. Gaydos, and M. C. Battigelli, http://bordeninstitute.army.mil/published_volumes/occ_health/OHch10.pdf last accessed Jun. 16, 2007].
Such conventional primer compositions require expensive handling procedures during both production and disposal. Several tons of these toxic materials and heavy metals are used annually by U.S. commercial suppliers in the production of percussion primer compositions. The Navy uses electric Gattling guns (20 mm and 25 mm) that fire hundreds of rounds per minute and subject Naval personnel to air-borne lead. Further, lead contamination of firing ranges (indoor and outdoor) costs the United States government millions of dollars a year in remediation costs. To reduce these costs, a joint effort between the government and industry is currently trying to develop less environmentally damaging ammunition for military applications.
The detrimental health effects of lead exposure in humans are well known [http://www.epa.gov/lead last accessed Jun. 16, 2007]. Lead exposure by inhalation or digestion can have serious health consequences such as heavy metal poisoning, nervous system disorders, kidney damage, and liver damage, for example. The adverse health effects may also include gastrointestinal, cardiovascular, renal, immunological and hematological disorders, and death. Environmental concerns about the hazards of lead exposure in the manufacturing process and during firing of small caliber ammunition in enclosed firing ranges have prompted ammunition manufacturers to develop lead-free primer alternatives, primarily based on diazodinitrophenol (DINOL) [Olin MSDS No. 00094.0001, http://www.winchester.com/pdf/MsdsPDF/msds_w94.pdf last accessed Jun. 16, 2007].
While the DINOL based lead-free primers are sold for commercial applications, such compositions have not met more stringent military requirements. For example, primer compositions used in military applications must function reliably at temperatures in the range of −65° F. to 165° F. However, the functional reliability of DINOL based primers decreases with decreasing temperature. The fact that externally mounted aircraft weapons are routinely subjected to severe cold conditions renders the low temperature performance of primer compositions extremely important, as weapon hang fire/misfire can have serious adverse consequences. While current DINOL primer compositions satisfy the requirements of ordinary commercial applications, such compositions do not function reliably at all temperatures between −65° F. and 165° F.
U.S. Pat. No. 5,266,132 issued on Nov. 30, 1993 to Danen, et al., which is assigned to the U.S. Government, teaches energetic nanoscale compositions, which consist of layers of two reactive substances, which are aluminum and cupric oxide, wherein the layers are formed by thin film deposition. In this composition each layer of aluminum is separated from at least one layer of cupric oxide by a buffer layer. However, the all-up round action times for the nanoscale metal-metal oxide formulations are much too long (50-500 milliseconds), as military requirements for DOD application are less than 4 milliseconds.
U.S. Pat. No. 5,717,159 issued on Feb. 10, 1998 to Dixon, et al., also assigned to the U.S. Government, teaches the use of nanoscale composites for percussion primer application. The U.S. Department of the Army developed and tested these metastable interstitial composite (MIC) primers, but found that the ignition delay was greater than 50 milliseconds, compared to less than 4 milliseconds for conventional lead-based primers. These MIC primer ignition delay times were not suitable for many military applications requiring high firing rates.
It is an object of the invention to provide improved primer compositions which do not contain toxic materials and whose by-products are essentially non-toxic and environmentally benign.